add hw2

node_modules/readable-stream/lib/internal/streams/passthrough.js

@@ -0,0 +1,39 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+// a passthrough stream.
+// basically just the most minimal sort of Transform stream.
+// Every written chunk gets output as-is.
+
+'use strict'
+
+const { ObjectSetPrototypeOf } = require('../../ours/primordials')
+module.exports = PassThrough
+const Transform = require('./transform')
+ObjectSetPrototypeOf(PassThrough.prototype, Transform.prototype)
+ObjectSetPrototypeOf(PassThrough, Transform)
+function PassThrough(options) {
+  if (!(this instanceof PassThrough)) return new PassThrough(options)
+  Transform.call(this, options)
+}
+PassThrough.prototype._transform = function (chunk, encoding, cb) {
+  cb(null, chunk)
+}